5-Fluoro-2-methyl-1-(p-methylsulfinylbenzylidene) -3-indenyl acetic acid is a known compound having antiinflammatory activity as disclosed in U.S. Pat. No. 3,654,349. The compound has been prepared by a number of methods as disclosed in the above-mentioned patent as well as U.S. Pat. No. 3,870,753. In one of the methods described in U.S. Pat. No. 3,870,753, 5-fluoro-2-methyl-1-(p-methylthiobenzyl) indenylidene-3-acetic acid is isomerized in excess aqueous acid to produce 5-fluoro-2-methyl-1-(p-methylthiobenzylidene) indenyl-3-acetic acid, followed by oxidation to produce the desired compound.
It is an object of this invention to provide an improved method for isomerizing 5-fluoro-2-methyl-1-(p-methylthiobenzyl) indenylidene-3-acetic acid. It is a further object to prepare the desired compound via an improved process which is advantageous over the process described above.
It is a further object of the present invention to provide an improved method for preparing 5-fluoro-2-methyl-1-(p-methylsulfinylbenzylidene)-3-indenyl acetic acid by utilizing the improved isomerization step followed by oxidation to the desired product.